In the related art, this kind of power converting apparatus is provided with a DC-DC converter circuit which steps up or down voltage from a distributed power supply, a DC-AC converter circuit which converts output voltage of the DC-DC converter circuit into AC, and a control circuit which controls the DC-DC converter circuit to keep the output voltage of the DC-DC converter circuit at a voltage target value.
Since this kind of power converting apparatus outputs AC, a large ripple current with twice the frequency of the AC output from the power converting apparatus usually flows through an input current of the power converting apparatus and a reactor input current (hereinafter, these currents will simply be referred to as an “input current”). Therefore, there is a problem that the burden and loss of the reactor and a switching element of the DC-DC converter circuit become large.
In order to address this problem, a power converting apparatus in which a ripple component included in an input current of a DC-DC converter circuit is extracted in a control circuit and compensates for a control input of the DC-DC converter circuit using the extracted ripple component has been proposed (see Patent Literature 1).
In particular, in the power converting apparatus disclosed in Patent Literature 1, a control circuit generates a first error signal indicating an error between output voltage of a DC-DC converter circuit and a voltage target value, and compensates for an input of an output voltage controlling circuit of the DC-DC converter circuit with a second error signal indicating an error between the first error signal and the extracted ripple component.
The power converting apparatus disclosed in Patent Literature 1 attempts to cancel the ripple component included in the first error signal with the extracted ripple component described above. However, in order to completely cancel the ripple component included in the first error signal, it is necessary to let the ripple component included in the first error signal and the extracted ripple component exactly correspond with each other in the phase and amplitude and thus implement thereof is difficult in practice.
Consequently, there has been a problem in the power converting apparatus disclosed in Patent Literature 1 that since it is not possible to sufficiently suppress the ripple component included in the input current of the DC-DC converter circuit and to sufficiently reduce the burden and loss of the device in the DC-DC converter circuit, increasing efficiency, reducing size and lowering cost of the entire power converting apparatus cannot be achieved.